Manufacturers use the OEE calculator as a potent tool to measure equipment and production process efficiency. It offers a comprehensive assessment of a machine or system’s operational effectiveness and identifies areas for improvement. OEE is presented as a percentage, with higher values signifying superior performance.
Formula
OEE is calculated using the following formula:
OEE = Availability × Performance × Quality
Availability
Availability represents the percentage of time that equipment is available and ready for production. It takes into account downtime and can be calculated as:
Availability = (Operating Time – Downtime) / Operating Time
- Operating Time: The total time the equipment should have been running.
- Downtime: The time when the equipment is not available for production due to breakdowns, maintenance, changeovers, etc.
Performance
Performance measures the efficiency of the equipment when it is running. It considers factors like speed loss and can be calculated as:
Performance = (Ideal Cycle Time × Total Parts Produced) / Operating Time
- Ideal Cycle Time: The minimum time it should take to produce one part under optimal conditions.
- Total Parts Produced: The actual number of parts produced during the operating time.
Quality
This accounts for the quality of the output produced by the equipment and is calculated as:
Quality = (Good Parts Produced / Total Parts Produced)
- Good Parts Produced: The number of parts that meet quality standards.
Example of OEE Calculator
Let’s walk through an example to illustrate how the OEE calculator works.
Suppose a manufacturing facility operates a machine for a total of 480 minutes (8 hours). During this time, there is 60 minutes of downtime due to maintenance and changeovers. Each part has an ideal cycle time of 10 minutes, and the production yields 400 parts, with 380 meeting quality standards.
Using the OEE formula:
- Availability = (480 – 60) / 480 = 0.875 (87.5%)
- Performance = (10 * 400) / 480 = 8.33
- Quality = 380 / 400 = 0.95 (95%)
Now, calculate OEE:
OEE = 0.875 (Availability) × 8.33 (Performance) × 0.95 (Quality) ≈ 0.6925
So, the OEE for this machine is approximately 69.25%.
Most Common FAQs
A1: A good OEE percentage varies by industry and specific circumstances. In general, an OEE above 85% is considered excellent, while anything below 70% may indicate room for improvement.
A2: Improving OEE involves addressing issues in availability, performance, and quality. Reduce downtime through preventive maintenance, optimize machine speed, and enhance product quality to increase OEE.